Synthesis and characterization of a series of biodegradable and biocompatible PEG‐supported poly(lactic‐ran‐glycolic acid) amphiphilic barbell‐like copolymers

Abstract

A series of multihydroxyl (2, 4, and 8) terminated poly(ethylene glycol)s and their biodegradable, biocompatible, and branched barbell‐like (PLGA)n‐b‐PEG‐b‐(PLGA)n (n = 1, 2, 4) copolymers have been synthesized. The lengths of the PLGA arms were varied by controlling the molar ratio of monomers to hydroxyl groups of PEG ([LA+GA]0/[OH]0 = 23, 45, 90). Chemical structures of synthesized barbell‐like copolymers were confirmed by both 1H and 13C‐NMR spectroscopies. Molecular weights were determined by 1H‐NMR end‐group analysis and gel permeation chromatography. The result of hydrolytic degradation indicated that the rate of degradation increased with the increase of arm numbers or with the decrease of arm lengths. The thermal properties were evaluated by using differential scanning calorimetry and a thermogravimetric analysis. The results indicated that the thermal properties of barbell‐like copolymers depended on the structural variations. The morphology of (PLGA)n‐PEG‐(PLGA)n copolymers self‐assembly films were investigated by atomic force microscope, the results indicated that the microphase separation existed in (PLGA)n‐PEG‐(PLGA)n copolymers. Because of the favorable biodegradability and biocompatibility of the PLGA and PEG, these results may therefore create new possibilities for these novel structural amphiphilic barbell‐like copolymers as potential biomaterials. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3802–3812, 2008

Synthesis of three-arm block copolymer poly(lactic-<em>co</em>-glycolic acid)&ndash;poly(ethylene glycol) with oxalyl chloride and its application in hydrophobic drug delivery

“…As shown in Figure 3D, the T g of the 3S-PLGA was about 50.91°C, while 3S-PLGA-PEG was 47.5°C. The results showed that the T g of 3S-PLGA-PEG was lower than 3S-PLGA because the existence of PEG can affect the crystalline property of PLGA, which can reduce the T g of this polymer, 33,34 and suggested the PEG segment was linked with PLGA.…”

“Tree‐Shaped” Copolymers Based on Poly(ethylene glycol) and Atactic or Isotactic Polylactides: Synthesis and Characterization

“…[15] Recently, Lu et al reported PEG-supported poly[(lactic acid)-ran-(glycolic acid)] barbell-like copolymers as novel potential biomaterials, and disclosed that thermal properties depended on the structural variations. [16] Interestingly, asymmetric AB n -shaped copolymers, having a linear polymer chain made of PEG and n poly(L-lactide) arms of 2 kDa molecular weight, have been described by Cao and coworkers, and showed a strong molecular architecture dependence on thermal and crystallization behavior. [17] In this framework, by using a diverse chemical approach, we obtained an extended preparation of analogous ''tree-shaped'' copolymers, having a linear polymer chain (core) made of PEG monomethyl ether, from which not only stereoregular isotactic PLLA branches, but also stereoirregular, atactic PDLLA chains start (Scheme 1).…”

Linear-dendrimer type methoxy-poly (ethylene glycol)-b-poly (ɛ-caprolactone) copolymer micelles for the delivery of curcumin

“…The tetra-hydroxyl MPEG was synthesized as previously (Lu et al, 2008). The procedure was described as follows: A three-neck flask equipped with a magnetic stirring bar was charged with MPEG (20 g, 10 mmol), sodium (2.3 g, 100 mmol) and 60 mL of THF.…”